The present invention relates to concrete reinforcements, and in particular, to a device for supporting and spacing such reinforcements and a reinforcement assembly using the device. Typically, concrete is reinforced by mats or layers of reinforcing bar and/or welded wire fabric. Each reinforcement layer or mat is suspended within the concrete structure. During pouring of the concrete, especially during pouring of horizontal slabs, it is necessary to suspend the reinforcing steel above the surface on which the concrete is poured. Often, a second layer or mat of reinforcement steel is spaced above the first reinforcement steel layer or mat in the concrete structure. Therefore, a supporting and spacing device is necessary to hold the reinforcement steel mats in their designated positions while the concrete is poured. The supporting and spacing device remains in the hardened concrete structure.
These devices are referred to herein as support spacers. Prior artisans often refer to them as "chairs".
A very common type of support spacer used to position such reinforcement steel mats is comprised of a small concrete block with a length of rebar protruding from the concrete, the rebar being bent into an L-shape at its free end. These support spacers are placed throughout the concrete structure, a first reinforcement steel mat being laid on the concrete blocks, and a second reinforcement steel mat being laid upon the L-shaped bent portion of the rebar member to hold the second reinforcement steel mat parallel to and a distance above the first.
One problem with the concrete block approach is that the top reinforcement steel mat can slide off of the L-shaped rebar member necessitating that the top reinforcement steel mat be tied to the L-shaped rebar member with a short piece of twisted wire. Having to tie the top reinforcement steel mat assembly to each support spacer in a large concrete structure requires considerable time and money in view of the high prevailing labor costs. Also, twisted wire has a tendency to break under load and the reinforcing members are free to move from their intended installed position.
Another problem with such concrete block spacers is that the lower reinforcement mat can slide off the concrete blocks while the concrete is being poured. Also, even though the top reinforcement mat is tied to the L-shaped rebar, the support spacer can be easily tipped over if the top reinforcement mat is located too close to the free end of the bent L-shaped rebar member. These conditions will cause the reinforcing members to be displaced from their installed and designated positions within the concrete structure. If the reinforcing steel layer or mat moves from its designated position, the cover concrete thickness above and below the reinforcing members is either increased or decreased. Recent studies have found that when the steel reinforcement is not positioned properly, deterioration of the concrete and reinforcement steel is greatly accelerated, especially in concrete roadways and parking structures where salt is applied in the wintertime.
Another critical problem with the concrete block spacer is that concrete blocks produce a non-uniform concrete structure. This can lead to stress discontinuities between the block and the poured concrete.
Another example of such a spacer is disclosed in Malsbur U.S. Pat. No. 2,754,764 entitled "REINFORCED CONCRETE BEAM SUPPORT" which shows a rebar with a U-shape bent free end, allowing two wire assemblies to be tied onto the bent area and a third assembly to be layered on a concrete base. Another type of spacer is disclosed in U.S. Pat. No. 1,772,741 entitled "REINFORCING STIRRUP ASSEMBLY" issued to Barber which comprises an inverted V-saddle on which a reinforcing assembly rests.
An inverted "V" spacer with a rebar rod support clip welded to its top is disclosed in U.S. Pat. No. 3,114,221 issued to Eriksson entitled "BROAD-SUPPORTING CHAIR FOR CONTINUOUSLY REINFORCING CONCRETE PAVING." By bending the tabs on the clip, one locks the rebar in place. However, the clip can break off the support and seems particularly susceptible to such breakage when the clip is bent by foot as shown in the patent. Also, such an assembly is expensive to manufacture.